The invention is based on an electromagnetic valve with at least one coil containing at least one coil former.
Electromagnetic coils are used in electromagnetic valves in order to control valve bodies which interact with valve seats using electromagnetic forces. Electromagnetic valves of this type are used, for example, in electronically controlled brake systems (EBS) of utility or commercial vehicles and, as a function of being fed with current, switch or control brake or control pressures.
Depending on the field of use, different operating voltages are applied to these valves. In the case of commercial vehicles used in the United States, an on-board voltage of 12 volts is customary, whereas in Europe this voltage is generally 24 volts. However, with the exception of the different operating voltages, the power data of the 12-volt and 24-volt solenoid valves should be substantially identical.
To date, in each case one integral wire winding with a wire diameter of approximately 0.3 to 0.5 mm and a relatively high number of turns has been used in the coils for 12-volt solenoid valves in order to achieve a required minimum electrical and/or magnetic power. As a result, a coil of this type is relatively large. In order to achieve approximately identical power values, a coil wire with a smaller wire diameter of approximately 0.2 to 0.3 mm is, in contrast, used in the case of the coils for 24-volt solenoid valves, as a result of which the 24-volt coils are approximately 20% smaller than the 12-volt coils. As a result of this, it is necessary to design the respective receptacles for the differently sized coils on otherwise identical solenoid valves with different dimensions, and this increases the outlay on production in a disadvantageous manner.
Furthermore, solenoid valves of this type, which are used in electronically controlled brake systems (EBS), are generally used in so-called pressure control modules as inlet, outlet and back-up valve combinations mounted close to the wheel or axle, where there is usually only a small amount of installation space available. It is therefore necessary for solenoid valves to be as small as possible. This also applies to solenoid valves for other applications, for example, to solenoid valves in transmission control systems.
The invention is based on the object of developing an electromagnetic valve of the above-mentioned type such that it can be operated at different operating voltages without major changes and, at the same time, be as small as possible. A method for producing such a valve is also specified.
According to the invention, an electromagnetic valve has at least one coil containing at least one coil former. The coil former is provided with at least two separate wire windings of which, in each case, two are connected in series or in parallel with one another. Such a coil is produced by providing at least one coil former of the coil with at least two separate wire windings; connecting, in each case, two wire windings in series or in parallel with one another; and providing the electromagnetic valve with the correspondingly connected coil.
The invention is based on the idea that the coil former of the coil of the electromagnetic valve is provided with at least two separate wire windings, of which in each case two are connected in series or in parallel with one another. This coil former contains, for example, only two wire windings which are connected in series or in parallel. Furthermore, a large number of combinations is feasible, for example four wire windings, of which the first and the second wire windings are connected in parallel with one another, the second and the third wire windings are connected in series with one another, and the third and fourth wire windings are again connected in parallel with one another.
In particular, the number of wire windings and the winding parameters of the wire windings, such as the wire diameter and/or number of turns, are selected in such a way that the coil to which predetermined different operating voltages are applied supplies substantially identical electrical and magnetic characteristic variables, such as electrical power and/or magnetic power, as a function of the connection of its wire windings.
For example, a wire which is thinner than that used in the prior art, in particular with a wire diameter which corresponds to that of the wire winding of a coil of a 24-volt solenoid valve, can be used for the wire winding of a coil for a 12-volt solenoid valve. When the wire winding additionally has the same number of turns as in the coil of the 24-volt solenoid valve, assuming the coil formers are the same size, a coil for a 12-volt solenoid valve which is the same size as the coil for a 24-volt solenoid valve is produced, so that the coil holders and, in particular, the coil holes in the valve housings of the electromagnetic valves can be formed with identical geometric dimensions.
Since the rest of the components, apart from the coil, of a 12-volt solenoid valve and a 24-volt solenoid valve should not differ from one another as far as possible, and the switching characteristics in both cases should be as identical as possible, approximately identical electrical variables, for example the electrical power and magnetic power, of the coils in the 12-volt solenoid valve and in the 24-volt solenoid valve are desirable.
This is achieved, according to the invention, in that, for an embodiment as a 12-volt solenoid valve for example, the originally integral wire winding with a thick wire is separated into two separate wire windings of the same size, which wire windings are connected in parallel with one another. In contrast, the two wire windings for the coil of the 24-volt solenoid valve are connected in series. The only difference between a coil for a 12-volt solenoid valve and a coil for a 24-volt solenoid valve is, accordingly, only the respective connection of the two wire windings, this constituting an extremely simple measure in terms of production. The rest of the design of the coils, for example the number of turns, the wire diameter or the coil former, is otherwise identical, this also making it necessary for the coils to have the same physical size.
A method for producing the described electromagnetic valve includes at least the following steps:
a) providing at least one coil former with at least two separate wire windings;
b) connecting in each case two wire windings in series or in parallel with one another as a function of the operating voltage; and
c) providing the electromagnetic valve with the correspondingly connected coil.
Accordingly, the invention can be used to produce types of solenoid valves for different operating voltages, but with the same power data, by using a coil which is matched to the respectively required operating voltage only by corresponding connection of the two wire windings and which is otherwise standard, in a similarly standard solenoid valve. This saves on expensive production and storage of different coils and solenoid valves.
The result is a higher electrical power than the prior art given the same installation space for the coil, or a smaller installation space than the prior art given the same power of the coil. This saves, in particular, on copper wire, as a result of which the production costs for the solenoid valves are reduced.
Other objects, advantages and novel features of the present invention will become apparent from the following detailed description of one or more preferred embodiments when considered in conjunction with the accompanying drawings.